Implications of a full straight through exhaust

Hi all,

What are the implications of having a true straight through exhaust on a TD5. No centre box, no back box, no cat, no baffles at all. From manifold/downpipe all the way to out the back?

Will there be an issue with back pressure? Noise obviously. Emissions?

Ta

huffhuff said:

Hi all,

What are the implications of having a true straight through exhaust on a TD5. No centre box, no back box, no cat, no baffles at all. From manifold/downpipe all the way to out the back?

Will there be an issue with back pressure? Noise obviously. Emissions?

Ta

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Seeing as the car would be illegal fines maybe the biggest problem.

wammers said:

Seeing as the car would be illegal fines maybe the biggest problem.

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Oh, why illegal?

huffhuff said:

Oh, why illegal?

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It is illegal to emit unsilenced gases. Vosa or a copper would have a field day if you got pulled. But your call.

I wasn't aware of this. Can you point to some legislation? I thought the only thing you could get pulled on would be the noise if deemed anti-social?

Not sure about legislation but I've seen a car fail MoT with a straight through exhaust. I've fitted a decat pipe and centre silencer delete (but kept the back box) on my Td5 and it sounds great - plenty of rumble and turbo whistle. No probs with MoT or coppers either. Why not just do that?

Used to have a straight through on mine, 300 tdi though. It flew through mot's with it on and unless you buried the throttle it really wasn't that noisy.

Can provide a link to said legislation?

2 of my mates have total straight throughs on Landys with no issues at MOT or otherwise (2001 TD5 & 300TDI). I have decat/straight thru but kept the rear most box, no issues (2002 TD5). Another mate has a Nissan S15 total straight through again no issues.

With the decat/straight thru its loud enough, any more and I think it would be a pain on long journeys.

bankz5152 said:

Can provide a link to said legislation?

2 of my mates have total straight throughs on Landys with no issues at MOT or otherwise (2001 TD5 & 300TDI). I have decat/straight thru but kept the rear most box, no issues (2002 TD5). Another mate has a Nissan S15 total straight through again no issues.

With the decat/straight thru its loud enough, any more and I think it would be a pain on long journeys.

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http://www.legislation.gov.uk/uksi/1986/1078/regulation/54/made Straight through unsilenced exhausts are illegal. See reasons for rejection item 4. http://www.motuk.co.uk/manual_710.htm

The MOTUK site seems to sound like if its just too loud and stupid then it will fail but not if its missing. Yet the first is very clear on the matter.

Anyway im sure there are many members on here running no boxes at all, side exhausts come to mind.

bankz5152 said:

The MOTUK site seems to sound like if its just too loud and stupid then it will fail but not if its missing. Yet the first is very clear on the matter.

Anyway im sure there are many members on here running no boxes at all, side exhausts come to mind.

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Maybe there are but they are still illegal. All vehicles MUST be fitted with a silencer.

I've got a single silencer on my 300tdi. No issues with MOTs. The rumble as it idles up the drive when my wife returns home with it is very distinctive.

thetim said:

I've got a single silencer on my 300tdi. No issues with MOTs. The rumble as it idles up the drive when my wife returns home with it is very distinctive.

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Your MOT tester is obviously deaf.

I had a straight-piped bobtail previously. That did fail an MOT on noise grounds! The single silencer is a lot quieter.

Straight through pipes will not meet the type approval that the vehicle initially gained, thus it could get into potential trouble as regards insurance if not declared. I used to run V8 RRCs with rear box only and no trouble with plod/mot, but I ran them on the company trade policy being a grease monkey at the time.

Many older discos have the back box removed to fit side-exit pipes, but I imagine most of them keep the centre box.

I think the noise would be the best/worst aspect depending on your viewpoint.

I took the CAT off my 110 TD5 and the drone at 65-70mph made long journeys a pain.

It wasn't a pleasant noise, just a droning.

With no silencers at all l'd not want to take it on the motorway!

I imagine if you got stopped you'd likely just get a rectification notice, as without getting it on a ramp you'd struggle to see what silencers were actually fitted.
But then it has to be inspected to make sure you've done it.

My question would be what advantages not what disadvantages. Apart from a few bhp I cant see any.

I'm not sure you'd see any more power. With no back pressure from silencers there may well be a reduction in BHP. Although l guess you could remap it to suit, on a rolling road.

The biggest advantage is you don't have to go through all the hassle of buying a Scooby and fitting a halfrauds dicktip for everyone to think you're a bellend

lightning said:

I'm not sure you'd see any more power. With no back pressure from silencers there may well be a reduction in BHP. Although l guess you could remap it to suit, on a rolling road.

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You won't get anything other than in the mind. Bit like the Kevin and his Corsa syndrome. It will just sound more powerful. Tuning an exhaust for better scavenging to improve BHP is an art, you don't tune an exhaust that's ten foot long simply by removing the silencers or fitting a bloody great tail pipe.